The ability to reason, to think, to contemplate, and to understand is a fundamental part of the human person. But I often hear it said that because of (S)in, our reasoining (like every other part of our humanity) is fallen. But if this is so, in what way? How does (S)in affect our reasoning? Is it fundamentally flawedbecause of (S)in? Does this make 'truth' beyond our grasp? I find the comments of Stephen C. Evans suggestive and helpful. He writes:
Insofar as sin is supposed to express itself in the desires and emotions of individuals, if reason is affected by those desires and emotions, then it is plausible that reason is affected by sin. We should be careful not to think that emotions always have a negative effect on reason... However, it is certainly true that emotions and desires can distort our rational faculties. If these emotions and desires are themselves distorted, which is atleast part of what it means to claim that humans are sinful, then it is logical to think that our reason may be distorted as well.
We are all aware of the reality of presuppositions, and how these affect our reasoning. Presuppositions can determine the direction of our reasoning from the beginning, they are inevitable (but not beyond scrutiny). Yet desires and emotions can be decisive in how honest we will be in our reasoning. Dispositions such as pride and arrogance can prevent us from honestly seeking the truth. The belief that we are right and cannot possibly be wrong can result in our refusing to listen to other prespectives because we feel that we already have the truth.
Kevin Vanhoozer writes that 'the fall into noetic sin implies that our knowing is corrupt, thus necessitating the counter-measure of epistemic virtue; and sanctification implies the cultivation of one virtue in particular-humility-for "redeeming" ones interpretative claims.'
In terms of interpreting texts (a significant activity in reasoning), Vanhoozer draws attention to what he refers to as 'Interpretive Virtues', 'disposition[s] of the mind and the heart that arises from the motivation for understanding, for cognitive contact with the meaning of the text.' He outlines four interpretive virtues: Honesty, Openness, Attention, and Obedience. Honesty consists in our being honest in acknowledging our presuppositions. Openness consists in our being 'open-minded', listening to other prespectives, being 'open' to the possibility that they are correct. Attention consists in attentiveness to details, a commitment to serious enquiry rather than jumping to quick conclusions. And obedience consists in taking what is grasped seriously, as something to act upon.
All too often we hear talk of axe-grinding, we read of how some scholars conservative or liberal background has apparently steered the course of their enquiry to confirm what they already believed. True, no-doubt it happens. But here is a call to Humility, to Honesty, and to Openness. To listen to the voices of others with the hope that what they have to say will take you beyond your present understanding, ever-closer to truth.
 Faith Beyond Reason: A Kierkegaardian Account (Eerdmans, 1998), 10
 'The Voice and the Actor: A Pragmatic Proposal About the Ministry and Minstrelsy of Theology', 89, in Stackhouse, J. G., Evangelical Futures: A Conversation on Theologicl Method (Baker, 2000)
 Is There A Meaning In This Text? The bible, the reader, and the morality of literary Knowledge (Apollos, 1998), 376
 Ibid., 377